Calculate the vapour pressure of pure water at 85 °C if a 285 mL solution containing 173.0 g of mannose, C₆H₁₂O₆, has a vapour pressure of 545.0 mbar. A) 531 mbar B) 578 mbar C) 508 mbar D) 599 mbar E) 520 mbar

Question

Quizplus · Accepted Answer

The vapour pressure of the solution is lower than that of pure water due to the presence of mannose. Using Raoult's law, the vapour pressure of pure water can be calculated by dividing the vapour pressure of the solution by the mole fraction of water. The mole fraction of water is calculated using the moles of water and mannose.

Calculate the Vapour Pressure of Pure Water at 85 °C